This invention relates to an integrated circuit in an ultrasound system and, in particular, for transmit and receive beamforming.
Ultrasound systems are coherent imaging systems. To generate information for imaging, ultrasound systems include transmit and receive beamformers. For example, U.S. Pat. No. 5,675,554 describes a transmit beamformer, and U.S. Pat. No. 5,685,308 describes a receive beamformer.
Transmit beamformers include circuits for generating a transmit waveform. If the transmit waveform is digital, the transmit waveform is converted to an analog transducer excitation waveform. The analog waveform is amplified, and multiplexed to a transducer.
For the transmit beamformer of U.S. Pat. No. 5,675,554, the transmit beamformer circuits of FIG. 4 and digital to analog converter (DAC) switches are provided on one integrated circuit (IC) for each channel or each pair of channels. See column 29, lines 2-7. The resistors and other active circuits of the DAC are located separately from the IC. In this system, the DAC, transmit amplifier, and IC components are located on a transmit circuit board, and the multiplexer components are located on a multiplexer circuit board.
Receive beamformers typically include circuits for coherently summing echo signals from multiple transducer elements. The echo signals are multiplexed from the transducer to amplifiers. If the receive beamformer comprises digital processing circuits, the echo signals are converted from analog signals to digital signals. The digital echo signals are coherently summed. The summed signals are provided for further processing and scan conversion to generate an image. For the receive beamformer of U.S. Pat. No. 5,685,308, the receive beamformer circuits and the analog to digital converter (ADC) circuits comprise different devices. Furthermore, the receive beamformer and the ADC circuits are located on a beamformer board. The receive amplifiers are located on a receive board.
In "An Ultrasound Beamformer Using Oversampling," 1997 IEEE ULTRASONICS SYMPOSIUM, pages 1687-690, S. R. Freeman et al. disclose integrating onto one chip all array processing elements for receive and transmit processing. Furthermore, integration of A/Ds onto a chip with the digital processing elements forming beams is disclosed. In particular, circuitry for signal processing echo signals and a modulator portion of a Sigma Delta ADC are integrated on a common IC. On page 1690, S. R. Freeman et al. disclose storing a transmit pulse in an on-chip memory and buffering to various digital delay structures. The samples are clocked through the system just as done for receive, but in the end they are converted to high voltage drive signals that synthesize a fixed focus transmit beam.
Transceivers for transmission and reception processing are used in various communications and computer devices. These transceivers may comprise one IC. ADC, DAC and digital signal processing (DSP) functions may be integrated onto the communication or computer transceiver IC. Typically, the IC is a Complementary Metal Oxide Semiconductor (CMOS).